Electrophotographic image formation is generally performed in a serial process of forming an electrostatic latent image on a photoconductor, developing the electrostatic latent image with a developer to form a toner image, transferring the toner image to a recording medium such as paper, and fixing it thereon.
As developers, one-component developers made of only either a magnetic toner or a non-magnetic toner, and two-component developers made of a toner and a carrier are known.
A toner image fixing method that is generally employed is a heating roller method of directly pressing and fixing a toner image on the recording medium by a heating roller, because this method is energy-efficient.
The problem is, however, that the heating roller method requires a great amount of electricity to fix a toner image.
Hence, enhancement of toner's low-temperature fixability is required.
PTL 1 discloses an image forming toner that contains a colorant, a binder resin, and a releasing agent, where the binder resin contains two kinds of polyester resins, namely a polyester resin A and a polyester resin B. The polyester A is a crystalline aliphatic polyester resin that has at least one diffraction peak at a position of 2θ=20° to 25° in its powder X-ray diffraction pattern. The polyester resin B is a non-crystalline polyester resin that has a softening temperature [T(F1/2)] higher than the softening temperature [T(F1/2)] of the polyester resin A. The polyester resin A and the polyester resin B are incompatible with each other.
However, it is required to prevent occurrence of toner scattering and background smear.